The present invention relates generally to high temperature superconductors. More specifically, the present invention relates to the fabrication of the high temperature Tl--Ba--Ca--Cu--O superconductors.
U.S. patent application Ser. No. 155,247, filed in the name of the inventors, of the present patent application discloses, in part, Tl--Ba--Ca--Cu--O superconductors that were discovered by the present inventors. These Tl--Ba--Ca--Cu--O superconductors have a transition temperature up to and above 120 K., this transition temperature, the inventors of the present patent application believe, is the highest to date among all existing high temperature superconductors.
For useful operation, the transition temperature of a superconductor typically must be at least 1/3 higher than the temperature of operation. For this reason, the Tl--Ba--Ca--Cu--O system has been called the first real liquid nitrogen temperature superconducting system.
The present existing procedures of preparing Tl-based superconductors involve the mixing of all component elements followed by a final sinter. Since Tl.sub.2 O.sub.3 evaporates easily, the quality of the Tl-samples is not easily controlled. In addition, in view of its toxicity, Tl.sub.2 O.sub.3 presents an additional set of difficulties during the fabrication of these types of superconductors.
An improved method for making Tl--Ba--Ca--Cu--O superconductors would be desirable for many reasons. Such a process would: (1) allow Tl-based superconductors to be easily constructed in the forms of complex bulk components, wires and fibers, and thick and thin films; (2) minimize the toxicity problem caused by Tl compounds; and (3) provide low cost processing and manufacturability.
Accordingly, there is a need for a new process of making Tl-based high temperature superconductors.